Filters are "saved searches"
so type that into the search bar, the save it with the green + at the end of the bar (you can give it a name)
That name now is available in the 'Filter box at the Left. (The blank at the top of the list, is how you un-filter).
Filters/saved searches are managed in the 'Tag Browser'

Ooooooh! Ok. Thank you!!

Quote:

Originally Posted by Starson17

That search is also a nice way to separate book records with no formats (paper books - wish list books, etc.) from actual e-book records.

Yes, I agree, that would be an excellent option if only it were feasible. My family, however, has way too many physical books to even think of adding our entire library to Calibre.